1. Field of the Invention
The present invention relates generally to alarm systems used in signaling the presence of oil and/or water in a confined area and, in particular, concerns such an alarm system that can be used in conjunction with submersible pumps in areas such as transformer vaults and elevator shafts to detect pump malfunctions and substantially prevent oil leaks from being pumped with water into the environment.
2. Description of the Related Art
Important technological infrastructure, such as electrical hardware and elevator hydraulics and cables, are often located in enclosed spaces such as transformer vaults and elevator shafts. This infrastructure is enclosed for a variety of reasons, including engineering design, prevention of injury or theft, noise dampening, and aesthetics. However, these enclosed spaces are often subject to waste water accumulation as water from rain, irrigation, leaks, and other sources may enter these spaces, accumulate, and flood the enclosure.
To prevent water from rising above a certain level in these enclosed spaces, submersible pumps are often used to remove accumulated water from these locations. The water is typically pumped into a reservoir and ultimately released into the environment via a sewer system or the like. However, when submersible pumps malfunction, the accumulated waste water can reach an unacceptable level thereby flooding the enclosed space and damaging the equipment therein. Additionally, the waste water is often mixed with oil that leaked from the equipment in these structures. This oil-water mixture presents an environmental hazard if it is pumped into the sewer system.
One solution which has been developed for this problem is the use of a mechanical float switch interconnected to an oil sensor and a pump. As the water level in the enclosed space changes, the float switch moves up and down on the surface of water. The resulting tilting movement is sensed by an internal switch within the float and triggers the pump to activate. If the oil sensor detects oil, the pump is not allowed to activate, while if oil is not detected, the pump is allowed to activate.
However, these float switches could be problematic as a level sensing device. Float switches are relatively imprecise, as they do not trigger at a set level but rather trigger based on a tilting motion. As a result, there is a relatively wide water level range over which the float may trigger. This range is further widened should the water be turbulent. Furthermore, the mechanical trigger within the float may fail over time due to wear or fatigue.
In view of the foregoing, there is need for an improved alarm system which detects the presence of water so as to provide an alert that water has accumulated beyond a predetermined location. Further, there is need for an alarm system which is capable of differentiating between water and oil.